The present invention relates to a power supply system, and more particularly, to a power supply system having a plurality of power supply devices with a redundant power supply device.
An example of this type of a conventional power supply system is disclosed in Japanese Patent Application Laid-Open No. Hei 5-274061. The power supply system disclosed in this publication is designed such that a plurality of power supply modules are connected in parallel. Each of the plurality of power supply modules includes a switching circuit that outputs an output voltage by a switching operation and an abnormality detecting circuit that detects an abnormality of the output voltage outputted from the switching circuit. In the conventional power supply system of this type, when the abnormality occurs in at least one of the plurality of power supply modules, the abnormality detecting circuit connected to an abnormal power supply module detects the abnormality and outputs an abnormality signal. The abnormality signal outputted from the abnormality detecting circuit is inputted to the corresponding switching circuit, and then, the switching circuit stops its switching operation. At the same time, the switching circuit makes an LED corresponding to the abnormal power supply module turn on. Upon recognizing that the LED is luminous, a maintenance keeper removes the power supply module corresponding to the luminous LED, whereby the abnormal power supply module is removed from the power supply system.
In the above-described conventional power supply system, even if it has a redundancy, it cannot be discriminated whether abnormality occurs in an essential power supply device for the power supply system or in a redundant power supply device. Therefore, the conventional power supply system has a problem that the entire power supply system must be stopped to remove the abnormal power supply device, even in a case where there is no necessity of stopping the entire power supply system because the abnormality merely occurs in the redundant power supply device.